Elastomers prepared from liquid polymers which exhibit good fuel, water and temperature resistance are very important commercial products. One way the prior art has attempted to produce such polymers is by condensing sodium polysulfide and dichloroethyl formal. The resulting polymer and many disadvantages including acid and water sensitivity and limited elevated temperature resistance. Improved fuel resistance has been achieved with ether-thioether polymers made by condensing beta-thioether alcohols in the presence of acid catalysts, e.g. as shown in U.S. Pat. No. 4,366,307. Such condensation is achieved by using high temperatures (e.g., 150.degree. C. or higher) and intense dehydration. Moreover, it is impossible, using polyols, to eliminate the oxygen in the polymeric backbone or to obtain directly mercaptan terminals during condensation and it is very difficult to increase the sulfur to oxygen ratio in the polymer which, we have found, increases the polymer's resistance to water.
U.S. Pat. No. 3,317,486 discloses the reaction between mercaptoethanol and the mixture of alpha and beta-mercaptopropanol. This reaction, according to the patent, produces a solid copolymer of randomly distributed isomers along the backbone. In column 3, lines 37-41, it is stated that regardless of which isomer is used the copolymer will be substantially the same.
The '486 patent preferably uses an approximately equimolar ratio of reactants but irrespective of the ratio, the patent states that the resulting copolymer is a solid, generally either waxy or powdery, and cannot be vulcanized. Moreover, the solid polymers produced by this patent have one terminal mercaptan group and one terminal hydroxyl group and therefore, even if liquid, these polymers could not be cured by any common commercial